Oxygen vacancies mediated enhanced visible-light-driven photocatalytic oxidation of biomass derived 5-hydroxymethylfurfural over V2O5·nH2O/g-C3N4 composite

A series of V2O5·nH2O/g-C3N4 (HVO/CN) heterogeneous composites were synthesized using an ultrasonic method and employed in the photocatalytic oxidation of 5-hydroxymethylfurfural (HMF) towards 2,5-diformylfuran (DFF). The HVO/CN-5 catalyst exhibited the highest photocatalytic performance with a 35.7 % yield and a 84 % of selectivity of DFF under visible light irradiation. A thorough investigation on the synthesized HVO/CN composite was executed to reveal the origin of the high photoactivity. The research results showed that the incorporation of HVO into CN widened the range of the visible-light response and improved the ability to separate the photo-induced charge carriers via a Z-scheme mechanism. Meanwhile, an increased concentration of oxygen vacancies was also observed in the composite, which enhanced the surface OH− content and facilitated the generation of hydroxyl radicals. This change is beneficial to the photocatalytic reaction since that hydroxyl and superoxide radicals are the main reactive species. A possible reaction pathway for the photocatalytic oxidation of 5-HMF to DFF was also suggested. This work may provide insights on the green and sustainable conversion of HMF to DMF via photocatalysis.